Impact of Maternal Age on Singleton Pregnancy Outcomes in Primiparous Women in South Korea.

We aimed to determine the association between maternal age and pregnancy outcomes in singleton primigravidae in South Korea. We reviewed the medical data of singleton primigravidae women who gave birth between 2013 and 2018 and underwent the National Health Screening Examination using the administrative database from the National Health Insurance claims data. As advanced maternal age is associated with various comorbidities that could affect pregnancy outcomes, we divided the patients according to their age and comparatively analyzed the prevalence of high-risk pregnancy complications including rates of cesarean delivery, after adjusting for maternal demographics. Perinatal and postpartum complications according to maternal age were also investigated. Overall, 548,080 women were included in this study: 441,902 were aged <35 years; 85,663, 35-39 years; 20,515, ≥40 years. Patients' demographics differed according to their age. Increasing maternal age was significantly associated with higher income levels and higher rates of obesity, pre-existing diabetes, and hypertension. With the increasing maternal age, the rate of obstetric complications, including gestational diabetes, preeclampsia, placenta previa, placental abruption, and cesarean delivery, increased. Maternal age was also positively correlated with perinatal morbidity including preterm birth and low birth weight. Additionally, advanced maternal age was a risk factor for hospitalization before delivery, more frequent outpatient visits, and readmission after delivery. These observations were maintained in the multivariate analysis results. Advanced maternal age appears to be associated with various adverse obstetric outcomes for primigravidae women, and the frequency of hospitalizations was higher in this group. Considering the current social environment of late pregnancies and childbirth in South Korea, effective policy consideration is required to support safe childbirth in women with advanced maternal age.